Search Results (28)

Bovine mastitis causes significant economic losses in the dairy industry. Emerging evidence highlights the critical role of long non-coding RNAs (lncRNAs) in inflammation-associated epigenetic regulation through competing endogenous RNA (ceRNA) networks. In this study, we established a bovine mastitis model in three healthy primiparous Holstein cows by intramammary infection with S. aureus. Infected and control mammary tissue samples were then collected for transcriptomic profiling, which identified 2005 differentially expressed lncRNAs. Among them, BMNCR was significantly upregulated in S. aureus-infected mammary tissues and S. aureus-stimulated BMECs. We evaluated the coding potential of BMNCR and confirmed its non-coding nature. Functional studies in BMECs demonstrated that knockdown of BMNCR suppressed proliferation, promoted apoptosis, and altered the expression of inflammatory factors, including IL-2, IL-6, IL-8, and IL-12. Mechanistically, BMNCR acted as a sponge for bta-miR-145, thereby leading to the derepression of ANO6. Silencing ANO6 partly recapitulated the effects of BMNCR knockdown, impairing proliferation and increasing IL-8 expression. Collectively, these findings suggest that the BMNCR/miR-145/ANO6 axis is involved in the regulation of inflammatory responses and epithelial homeostasis during bovine mastitis, with BMNCR functioning as a protective regulator in this process. Full article

Somatic cell count (SCC) in milk is widely used as an indicator of intramammary infections in dairy sheep and is routinely monitored by the dairy industry as a marker of milk quality. This study aimed to evaluate the effect of SCC levels on milk production, composition, colour, coagulation properties, and cheese-making ability in Manchega dairy sheep. A total of 752 individual milk samples were analysed. To normalise SCC distribution, the somatic cell score (SCS) was calculated and samples were classified into SCS classes. Increasing SCS significantly reduced daily milk yield and lactose content, increased milk pH, and decreased lightness (L*). Higher SCS was also associated with impaired coagulation properties, including longer rennet clotting time (RCT) and curd firming rate (k₂₀), as well as reduced curd firmness (A₃₀, A₆₀). Similar effects were observed for modelled coagulation parameters, with delayed RCTeq and reduced kCF and CFp. Regarding cheese-making ability, SCS significantly affected curd humidity and protein recovery, whereas no significant effects were detected for dry curd yield or fat recovery. Overall, elevated somatic cell counts were associated with a reduction in the technological quality of Manchega sheep milk, particularly affecting coagulation behaviour and curd characteristics. These results underline the importance of controlling SCC levels in dairy sheep systems for both udder health monitoring and maintaining milk suitability for cheese-making. Full article

Staphylococcus aureus (S. aureus)-induced mastitis poses a significant threat to animal husbandry. This condition triggers sustained mammary inflammation, oxidative stress, and disrupts mitochondrial homeostasis, ultimately impairing mammary gland function and milk yield. Conjugated linoleic acid (CLA) is a long-chain fatty acid found in meat and dairy products derived from ruminants. It exhibits multiple biological activities, including anti-cancer, anti-inflammatory, and antioxidative stress-alleviating effects. Thus, this study sought to determine whether CLA alleviates S. aureus-induced mastitis in Hu sheep through the PPARG-UCP2 axis. Fifteen lactating Hu sheep were randomly allocated into three groups (n = 5): control group, model group, and CLA group. The CLA group received 1 mg/mammary gland of CLA via intramammary infusion for seven days, followed by S. aureus challenge (5 × 10⁷ cells/mL, 2 mL/mammary gland) in the model and CLA groups, while the control group received saline. Venous blood and mammary tissue samples were collected at two days post-infection. The results demonstrated that S. aureus infection significantly upregulated the expression of inflammatory factors (IL-1β, IL-6, and NF-κB) in the mammary tissue of Hu sheep, p < 0.01. Relative to the control, the model group showed increased ROS and MDA levels, a diminished NAD+/NADH ratio, and downregulated expression of the antioxidant factors SOD, Nrf2, HO-1, and SIRT3, p < 0.01. Furthermore, the expression of p-AMPK and mitophagy-related factors (PARKIN, PINK1, and LC3b) showed a statistically significant increase in the model group than in the control group, p < 0.01. S. aureus infection also suppressed the expression of PPARG and UCP2, p < 0.01. In contrast, the CLA group showed lower levels of inflammatory factors (IL-1β, IL-6, and NF-κB), ROS and MDA, while the NAD+/NADH ratio and the expression of antioxidant factors (SOD, p-Nrf2, HO-1, and SIRT3) were elevated compared with the model group, p < 0.01. Moreover, the expression of p-AMPK and mitophagy-related factors (PARKIN, PINK1, and LC3b) was reduced in the CLA group relative to the model group, p < 0.05. Concurrently, the expression of PPARG and UCP2 was higher in the CLA group than in the model group, p < 0.001. These findings demonstrated that S. aureus infection induced mastitis in Hu sheep mammary tissue, whereas CLA alleviated the infection by upregulating the PPARG-UCP2 pathway, thereby reducing inflammation, oxidative stress, and mitophagy levels. This study offers a novel perspective on mammary tissue repair during mastitis and expands the understanding of UCP2’s biological role. Full article

This study investigated the relationship between milk composition among different mastitis pathogens. The study was conducted from January to February 2025 on three different dairy farms in Cambodia, utilizing 241 crossbred Holstein–Friesian milking cows. Quarter milk samples were aseptically collected from randomly selected milking cows, mostly in mid- and late lactation, including 450 samples from 3, 25, and 213 cows and 11, 88, and 351 quarters from Farms A, B, and C, respectively. The milk samples were analyzed for bacterial identification, somatic cell count, and milk composition. Mastitis pathogens were grouped primarily based on their genus, including streptococci, coagulase-negative staphylococci (CNS), Gram-negative bacteria (Gram-negative), CNS plus streptococci (Mixed), and those with no detected bacteria (None). Pearson’s correlation coefficients were used to determine the correlations between milk composition and somatic cell scores (SCSs). The comparison of milk composition and SCS means across bacteria groups, farms, and intramammary infection (IMI) status was performed using repeated linear models. Significance was defined as p < 0.05, and a tendency was defined as p < 0.10. The results show that the collected quarter milk had a low fat concentration. Milk composition and SCS were associated with the farm (p < 0.05). Regarding bacterial groups, the SCS of milk with streptococci was higher than that of milk with CNS and non-IMI milk (p < 0.05). Milk with a mixed IMI of streptococci and CNS had significantly lower lactose and solid-not-fat (SNF) levels than milk with CNS or Gram-negative bacteria. In contrast, the freezing point of the mixed IMI was higher than that of CNS and non-IMI milk (p < 0.05). In conclusion, the compositions of milk from CNS IMI did not deviate from those of milk from healthy quarters; however, the mixed infection of CNS and streptococci caused lower milk quality. These findings underscore the importance of CNS IMI, which can lead to significant economic losses in the case of infection with other pathogens. However, as this study employed a cross-sectional design, which is suitable for identifying associations rather than establishing causation, further studies are needed. Full article

The objective of this study was to evaluate the effects of feeding a combination of chicory–plantain silage and supplementing Se yeast on the response of early-lactating ewes to induce subclinical mastitis. Polypay ewes (n = 32) were fed either chicory–plantain silage or grass silage and supplemented with 3.6 mg Se yeast/ewe/day for approximately 2 months prior to the infusion of S. uberis into both mammary glands (i.e., intramammary infection or IMI). The ewes had a typical subclinical mastitis response with an 8-fold increase in milk somatic cell count within 24 h post-IMI, a decrease in milk yield, and changes in all milk components measured. The ewes experienced a mild systemic inflammation post-IMI as determined by an increase in rectal temperature and decrease in feed and water intake and, in blood, by an increase in the concentration of ceruloplasmin, haptoglobin, and myeloperoxidase and a decrease in paraoxonase, Zn, advanced oxidation protein products, and hematocrit with no effect on pro-inflammatory cytokines. No effect of silage type, likely due to a low concentration of secondary compounds, or Se supplementation was detected in response to IMI. In summary, the subclinical mastitis model used was effective in mounting an inflammatory response, although this was mild; however, feeding chicory–plantain silage with a low concentration of secondary compounds and supplementing Se yeast had no significant effect on the response of ewes to mammary infection. Full article

Sixty Holstein cows were enrolled at −76 days from calving (DFC) and classified based on the daily SCC during the previous week from an automated milking system. The separation thresholds for low (L, n = 46) and high (H, n = 14) classifications were 100 K/mL for primiparous and 200 K/mL for multiparous cows. Cows were then assigned to two homogeneous groups to receive diets supplemented with 19 g/d of a Saccharomyces cerevisiae fermentation product (TRT; NutriTek, Diamond V, Cedar Rapids, IA, USA) or without supplementation (CTR) until 60 DFC. Cows were dried off at −56 DFC and monitored for disease incidence, milk yield and composition, plasma metabolic profile, and whole blood count from −76 to 60 DFC. Data were analyzed utilizing ANOVA and mixed models for repeated measures. During the dry period, TRT cows had greater plasma thiol and albumin compared to CTR. TRT-L cows had greater plasma protein and globulin than CTR-L. TRT-H cows had heightened hematocrit; reduced plasma globulin and haptoglobin; and higher albumin, albumin to globulin ratio, and thiol than CTR-H. TRT-H cows had greater concentrations of leukocytes and lymphocytes and lower plasma protein and ceruloplasmin at −54 DFC; lower reactive oxygen species to ferric ion-reducing antioxidant power ratios at −44 DFC; and greater concentrations of lymphocytes and plasma gamma glutamyl transferase at −7 DFC than CTR-H. After calving, TRT cows had a lower incidence of mastitis and higher butterfat, as well as greater plasma haptoglobin and aspartate amino transferase (AST) and reduced Mg compared to CTR. TRT cows had lower SCC between 1 and 7 DFC and a greater ECM between 41 and 60 DFC compared to CTR. TRT-H cows had lower SCC between 1 and 7 DFC and greater hemoglobin and plasma AST than CTR-H. Ameliorated immune system functions due to Saccharomyces cerevisiae fermentation product administration lowered the SCC in TRT-H cows and prevented the onset of new intramammary infections across both L and H SCC groups, supporting the improved productive performance of dairy cows. Full article

Adopting a new milking system at a dairy farm causes various changes. This study examined the impact on udder health when changing from a conventional milking system to an automatic milking system. For this purpose, quarter milk samples were taken six times from 138 cows at one conventional dairy farm in Northern Germany over a five-week period around the time of the milking system changeover. To assess udder health, the absolute number of new intramammary infections and the causative pathogen genera and species were analysed for each individual study time point. Pathogen species were detected using matrix-assisted laser desorption ionisation time-of-flight, and the infection dynamics were analysed using two Poisson regression models. In addition, the prevalence and incidence of new intramammary infections and the infection dynamics of the four most frequently isolated pathogen species were calculated. Mixed models were used to determine the development of the new infection rate, the somatic cell count, the teat-end condition, and the udder hygiene between the individual study time points and to compare the new infection rate before and after the changeover of the milking system. After the automatic milking system had been installed, a significant increase in the quarter-level somatic cell count occurred (p < 0.001). Two days before the installation of the automatic milking system, the mean quarter-level somatic cell count was 11,940 cells/mL milk; one sampling date later, 8 days after the changeover, a mean quarter-level somatic cell count of 60,117 cells/mL milk was measured. The significant increase in somatic cell count was probably caused by the time between the last milking and the quarter milk sampling. Additionally, significantly more udders were scored as clean 8 days (95%) and 15 days (96%) after the changeover of the milking system compared to at the last sampling date (88%). Also, significantly more teat ends were classified as free of hyperkeratosis 15 days (80%) compared to 22 days (67%) after the changeover of the milking system. The highest number of absolute new intramammary infections was detected 8 days before the transition of the milking system (28.6%). The lowest number of absolute new intramammary infections occurred 8 days after the change to the automatic milking system (11.0%). Minor mastitis pathogens, such as non-aureus staphylococci and coryneform bacteria, were mainly responsible for the development of new intramammary infections. The most frequently isolated pathogen species were Staphylococcus sciuri, Staphylococcus chromogenes, Staphylococcus haemolyticus, and Corynebacterium amycolatum, with a prevalence of up to 23.9, 10.7, 8.4, and 5.3%, respectively. By comparing the new infection rate before and after the changeover of the milking system, it was possible to establish that the changeover to the automatic milking system had no significant influence on the new intramammary infection rate (p = 0.988). Therefore, this trial confirmed that the changeover from a conventional milking system to an automatic milking system had no negative influence on udder health. Full article

The microbial ecology in mastitis involves the interactions between bacteria and the mammary gland environment. Poor mastitis control, for which understanding these microbial relationships is crucial, increases the risk of mastitis and co-infections. The aim of this study was to determine the pathogenesis and bacterial ecology of murine mammary glands following intramammary infection (IMI) with S. aureus (AU), S. agalactiae (SA), and four isolates of selected non-aureus staphylococci (NAS), as well as co-infections of AU or SA with NAS. Selected NAS demonstrated resistance to growth inhibition after co-culture with AU and SA and were proven to be protective in vitro against AU and SA. Both single infections and co-infections of AU, SA, two selected isolates of S. hominis (NAS1 and NAS2), and two selected isolates of S. chromogens (NAS3 and NAS4) were injected into the murine mammary glands at 10⁵ CFU/mL. After 72 h of inoculation, the results showed that AU, AU–NAS2, and AU–NAS3 expressed severe inflammation with clinical signs of mastitis. The persistence of AU was found for AU, NAS3, and AU–NAS3, whereas the persistence of SA was found for SA–NAS1, SA–NAS3, and SA–NAS, although single SA could not persist. Interestingly, NAS2 in both the single- and co-IMIs with AU or SA resulted in a spontaneous cure 72 h after the IMI. In conclusion, some NAS have beneficial results because they can eliminate S. aureus and S. agalactiae, but some NAS have negative effects because they can support persistent S. agalactiae infection. These results may be used to explain both the advantages and disadvantages of NAS on farms with poor mastitis control. In addition, the beneficial S. hominis may initiate natural live antibiotics and reduce antibiotic resistance problems. Full article

Prevention of new intramammary infection (NIMI) during the dry period (DP) is essential to prevent the development of mastitis in dairy cows. To investigate risk factors for NIMI, 212 cows, comprising a total of 848 udder quarters, were examined in this study. Quarter milk samples were taken on the day of drying off and 7 ± 3 days after calving. Cow- and quarter-level associated risk factors were assessed at the beginning of the DP and after calving. In total, 7.1% of the udder quarters developed an NIMI between the samplings. Non-aureus staphylococci (40.4%) and Gram-negative pathogens (22.8%) were most frequently the cause of NIMI. The observed milk leakage prevalence was 16.7%, with a peak 24 h after drying off. Simultaneously, the udder pressure peaked 24 h after drying off. A significant correlation between milk yield on the day before drying off and milk leakage could be proven. Cows with quarters leaking milk produced an average milk yield of 28.32 kg on the day before drying off. Generalised linear mixed models and odds ratios were calculated to determine the significant risk factors for NIMI during the DP and early lactation. Quarters leaking milk had 3.4 higher odds for NIMI between the samplings compared to quarters without milk leakage. Quarters from cows with dirty udders had 3.1 higher odds of developing an NIMI between the samplings compared to quarters from cows with clean udders. The results of this study demonstrate the importance of dry cow management before drying off and during the critical period of active involution of the udder tissue. Full article

The aim of this study was to establish and evaluate a structural equation model to infer causal relationships among environmental and genetic factors on udder health. For this purpose, 537 Holstein Friesian cows were genotyped, and milk samples were analyzed for novel traits including differential somatic cell counts and specific mastitis pathogens. In the structural model, four latent variables (intramammary infection (IMI), production, time and genetics) were defined, which were explained using manifest measurable variables. The measurable variables included udder pathogens and somatic differential cell counts, milk composition, as well as significant SNP markers from previous genome-wide associations for major and minor pathogens. The housing system effect (i.e., compost-bedded pack barns versus cubicle barns) indicated a small influence on IMI with a path coefficient of −0.05. However, housing system significantly affected production (0.37), with ongoing causal effects on IMI (0.17). Thus, indirect associations between housing and udder health could be inferred via structural equation modeling. Furthermore, genotype by environment interactions on IMI can be represented, i.e., the detection of specific latent variables such as significant SNP markers only for specific housing systems. For the latent variable genetics, especially one SNP is of primary interest. This SNP is located in the EVA1A gene, which plays a fundamental role in the MAPK1 signaling pathway. Other identified genes (e.g., CTNNA3 and CHL1) support results from previous studies, and this gene also contributes to mechanisms of the MAPK1 signaling pathway. Full article

In Denmark, PCR testing of dairy cattle is commonly used to select animals for the antibacterial treatment of intramammary infection (IMI) during the dry-off period. IMI is associated with a high somatic cell count (SCC), routinely recorded for milk quality control for most commercial dairy herds. This study aimed to compare SCC curves over the lactation among dairy cows with positive vs. negative PCR test results for four major IMI pathogens. Data from 133,877 PCR-tested Holstein cows from 1364 Danish conventional dairy herds were used to fit a nonlinear mixed-effects model using a modified four-parameter Wilmink function. We stratified the data into first, second, third or fourth and later parity and fitted Wilmink curves to all SCC observations between 6 and 305 days in milk. The PCR tests were taken before dry-off at the end of the lactation to investigate which animals qualified for selective dry cow therapy. A PCR Ct-value of 37 and below was used to determine if an animal was PCR positive for any of the following IMI pathogens: Staphylococcus aureus, Streptococcus agalactiae, Str. dysgalactiae and Str. uberis. Our findings showed that mean SCC curve fits were higher for PCR-positive animals in all four parity groups and across lactations. The use of SCC data fitted to the entire lactation for multiple lactations enabled quantification of overall differences in SCC curves between cattle with and without detected IMI, adjusted for parity group and stage of lactation. These findings are relevant to the use of SCC to support treatment decisions. Full article

The economic evaluation of mastitis control is challenging. The objective of this study was to perform the economic evaluation of mastitis control, under different intervention scenarios, quantifying the total cost of mastitis caused by S. aureus in Holstein cows in Argentina. A model was set for a dairy herd of Holstein cows endemically infected with S. aureus. A basic mastitis control plan including proper milking procedures, milking machine test, dry cow therapy, and treatment for clinical mastitis, was compared against other more complex and costly interventions, such as segregation and culling of chronically infected cows. Sensitivity analysis was performed by modifying the intramammary infection transition probabilities, economic parameters, and efficacy of treatment strategies. The basic mastitis control plan showed a median total cost of USD88.6/cow per year, which was close to the infected cows culling scenarios outputs. However, the segregation scenario was the most efficient, in which the total cost was reduced by about 50%. Such cost was more sensitive to probabilities and efficacy than the economic parameters. The model is flexible and can be customized by producers and veterinarians according to different control and herd settings. Full article

Staphylococcus aureus causes intramammary infections (IMIs), which are refractory to antibiotic treatment and frequently result in chronic mastitis. IMIs are the leading cause of conventional antibiotic use in dairy farms. Phage therapy represents an alternative to antibiotics to help better manage mastitis in cows, reducing the global spread of resistance. A mouse mastitis model of S. aureus IMI was used to study the efficacy of a new cocktail of five lytic S. aureus-specific phages (StaphLyse™), administered either via the intramammary (IMAM) route or intravenously (IV). The StaphLyse™ phage cocktail was stable in milk for up to one day at 37 °C and up to one week at 4 °C. The phage cocktail was bactericidal in vitro against S. aureus in a dose-dependent manner. A single IMAM injection of this cocktail given 8 h after infection reduced the bacterial load in the mammary glands of lactating mice infected with S. aureus, and as expected, a two-dose regimen was more effective. Prophylactic use (4 h pre-challenge) of the phage cocktail was also effective, reducing S. aureus levels by 4 log10 CFU per gram of mammary gland. These results suggest that phage therapy may be a viable alternative to traditional antibiotics for the control of S. aureus IMIs. Full article

Antimicrobials are widely used to cure intramammary infections (IMI) in dairy cows during the dry period (DP). Nevertheless, the IMI cure is influenced by many factors and not all quarters benefit from antimicrobial dry cow treatment (DCT). To evaluate the true effect of antibiotic DCT compared to self-cure and the role of causative pathogens on the IMI cure, a retrospective cross-sectional study was performed. The analysis included 2987 quarters infected at dry-off (DO). Information on DCT, causative pathogens, somatic cell count, milk yield, amount of lactation, Body Condition Score, and season and year of DO were combined into categorical variables. A generalized linear mixed model with a random cow, farm and year effect and the binary outcome of bacteriological cure of IMI during the DP was conducted. In the final model, a significant effect (p < 0.05) on DP cure was seen for the DO season and the category of causative pathogens (categories being: Staphylococcus aureus, non-aureus staphylococci, streptococci, coliforms, ‘other Gram-negative bacteria’, ‘other Gram positive bacteria’, non-bacterial infections and mixed infections), while antibiotic DCT (vs. non-antibiotic DCT) only showed a significant effect in combination with the pathogen categories streptococci and ‘other Gram-positive bacteria’. Full article

Lactococcus garvieae (L. garvieae) is a pathogenic gram-positive, catalase-negative (GPCN) bacterium that causes bovine mastitis. A total of 49 L. garvieae isolates were identified from 1441 clinical mastitis (CM) samples. The pathogenic effects of L. garvieae were studied with two infection models: bovine mammary epithelial cells cultured in vitro and murine mammary infections in vivo. The overall farm prevalence was 15.5% (13/84 farms in 9/19 provinces) and sample prevalence was 3.40% (49/1441). Post-treatment somatic cell count (SCC) post L. garvieae infection was significantly higher than the other GPCN pathogens isolated, and the bacteriological cure fraction was 41.94% (13/31) after intramammary antibiotic treatment. All L. garvieae isolates were resistant to rifaximin, 12.24% of isolates were resistant to cephalexin, and 10.20% (5/49) were multidrug-resistant (MDR). The most prevalent virulence genes were Hemolysin 1 (hly1)(100%), Hemolysin 2 (hly2) (97.96%), NADH oxidase (NADHO) (100%), Superoxide dismutase (SOD) (100%), Adhesin Pav (Pav) (100%), Adhesin PsaA (PsaA) (100%), Enolase (eno) (100%), Adhesin cluster 1(AC1) (100%), Adhesin cluster 2 (AC2) (100%), and several exopolysaccharides. L. garvieae rapidly adhered to bovine mammary epithelial cells, resulting in an elevated lactate dehydrogenase release. Edema and congestion were observed in challenged murine mammary glands and bacteria were consistently isolated at 12, 24, 48, 72, and 120 h after infection. We concluded that L. garvieae had good adaptive ability in the bovine and murine mammary cells and tissue. Given the resistance profile, penicillin and ampicillin are potential treatments for CM cases caused by L. garvieae. Full article